make chapter optional and fix sentence about no transformers in this tutorial

Author: chrisweb

app/web_development/tutorials/next-js-static-first-mdx-starterkit/code-highlighting-plugin/page.mdx

@@ -701,7 +701,7 @@ function helloWorld() {
 
 With this language you can use the **+** and **-** signs to tell the code highlighter to display the rows starting with a plus sign as if they had been added and the rows starting with a minus sign as if they had been removed
 
-## Diff using a shiki transformer
+## Diff using a shiki transformer (optional)
 
 You can also use shiki transformers in your rehype-pretty-code setup, as we just saw in the previous chapter, to create diffs one way is to use a language flag, the second way is to use the [shiki diff notation transformer](https://shiki.style/guide/transformers)
 
@@ -1016,7 +1016,7 @@ If we used the correct tokens to create our aliases map, the colors in the list
 ![the result when using rehype pretty code for a code block and some inline code examples](../../../../../public/assets/images/app/web_development/tutorials/next-js-static-first-mdx-starterkit/rehype-pretty-code_code_block_and_inline_code_examples.png)
 
 > [!TIP]  
-> There are even more features like **shiki transformers**, **visitor hooks** and **custom highlighters** (which we will not see in this tutorial), but you can find more info about them in the [rehype pretty code](https://rehype-pretty.pages.dev/) and [shiki](https://shiki.style/) docs websites
+> There are even more features like **visitor hooks** and **custom highlighters** (which we will not see in this tutorial), but you can find more info about them in the [rehype pretty code](https://rehype-pretty.pages.dev/) and [shiki](https://shiki.style/) docs websites
 
 Congratulations 🎉 you finished learning about how to highlight code using a remark plugin and learned how to use most of its features (including using VSCode themes)